2013 saw a record harvest of 345,000 tonnes of grapes, up significantly from the low harvest last year.

New Zealand winegrowers chief executive Phillip Gregan said the survey pointed to signs of an industry turnaround.

"There's a level of optimism that was not present three to four years ago," Gregan said.

Deloitte partner Paul Munro said the second successive year of increased profitability across wineries showed a sustained turnaround in the industry, however the positive results clearly favoured the larger end of the market.

"Successful business models certainly exist within the smaller wineries but the survey results appear to show that it is more difficult to generate acceptable returns at the smaller end of the market," Munro said.

Wineries earning more than $20 million in revenue, were the most profitable - with an average profit of 16 percent, the survey found.

Munro said the 2013 survey indicates that profitability generally increases with the size of wineries and that a widening gap between big and smaller wineries opens the door for mergers and overseas acquisitions by wealthy investors.

"Overseas investment can be useful provided the investor's interests are aligned, and they have a level of emotional engagement and skills to bring other than just money," Munro said.

The survey estimates the New Zealand wine industry has an annual turnoverexceeding $2 billion with $1.21 billion of this coming from export earnings.